The Ephraimite hill country held the sanctuary at Shiloh, where the tabernacle and the ark stood before the monarchy and where Samuel was raised, and it held Bethel and Shechem, the two places where Israel is repeatedly said to have made covenant. Joshua, who led the conquest in the book that bears his name, was of Ephraim and was buried there. The territory was central, fertile and full of holy places, and the tribe behaved accordingly, quarrelling with Gideon and with Jephthah in Judges over not being called to a battle first.
When the kingdom split after Solomon, the leader of the northern secession, Jeroboam, was an Ephraimite, and the northern capital eventually settled at Samaria inside the same hill country. From that point the prophets use Ephraim as a name for the whole northern kingdom. Hosea, preaching in the north in its last decades, uses the word dozens of times, sometimes tenderly, as of a child taught to walk, and sometimes as a charge sheet. Isaiah warns Judah that within a fixed span Ephraim will be broken and no longer a people.
Assyria took Samaria in 722 BCE and deported its population, and the tribe as a political entity ends there. What survives is the name. The Samaritan community, still living in the same district, holds itself descended from Ephraim and Manasseh and maintains that its worship on Mount Gerizim is the older practice. And in later Jewish tradition a second messianic figure, Messiah ben Joseph or ben Ephraim, is expected to precede and to fall before the son of David, which keeps the northern claim alive in a form that survived the kingdom by millennia.